Federal jail would be a federal thing. There are federal prisons in CO, most notoriously the Supermax in Florence, but they don't put simple drug dealers in there. Federal arrests for pot in CO?
Most recent stats I found are 2010 http://www.ccjrc.org/pdf/2010_Colorado_Quick_Facts.pdf
Latinos/as account for 17.1% of the population in Colorado, but 31% of the state prison population.
• African-Americans make up 3.8% of Colorado’s population, but represent 19.4% of people in state prison.
• Anglos are 74.5% of the state’s population, but only 46% of the prison population
CO has private prisons too. I think that's nationwide these days, sadly.
Now bear in mind that pot has been de-facto legal in CO for about 4 years already. The Denver PD (largest city in the state) has been de-emphasizing pot enforcement for several years. There's been greater emphasis on other enforcement areas, like domestic violence and drunk driving.